Armature Mesh Deformation
Going by the image alone,  it seems like the nails might be the problem. I have seen figures with separate nail meshes and that causes problems with AW.

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One bit of unrelated advice, if this model is to be used in Blender, renaming your bones and adding .L and .R (left and right) at the end will greatly speed up your work. "Forearm.R" reads a lot faster than "Bone 50" and allows you acess to built-in functions like Paste Mirrored Pose

Edit

The next item on your checklist is to go into Weight Paint Mode and check if the messed up parts are (somehow) assigned to another bone.